Expandable conveyors are conventionally employed to convey items such as corrugated containers of product in warehouses, manufacturing facilities and other locations. For example, expandable conveyors may be employed at the terminus of conveyor branches in a warehousing rigid and fixed conveyor distribution system to extend from the branches of the central conveyor system in flexible fashion to accommodate various trucks and shipping containers. The conveyors may be moved, for instance, back and forth, left and right in order to accommodate the location in which a truck is parked and to direct the stream of items to the particular portion of the truck being filled.
Expandable conveyors often take the form of scissors or "lazy tongs" structures. These conventionally contain a pair of scissor structures which act as expandable load bearing members, between which a plurality of skate wheel or elongated rollers spans. The scissors members are connected, conventionally, at substantially their top and bottom portions and their midportions to each other to provide proper linkage, expandability, and strength. Various connections may obviously be omitted, such as midpoint connections, for manufacturing efficiency and other purposes.
Such expandable roller conveyors are disclosed in, for instance, U.S. Pat. No. 4,852,712 issued Aug. 1, 1989 to Best entitled "Conveyor" which discloses an extensible lazy tong conveyor. U.S. Pat. No. 5,224,584 issued Jul. 6, 1993 to Best, et al. entitled "Expandable Powered Conveyors" discloses power conveyors in which the power units are located external to the rollers and connected to them via a number of chains or belts. U.S. patent application Ser. No. 08/022,012 and now abandoned to Best, et al. filed Feb. 24, 1993 entitled "Controllably Powered Roller Conveyors" discloses powered lazy tong conveyors in which the power units are located within the rollers. All of these patent documents are incorporated herein by this reference.
It is often the case that expandable conveyors need to be repositioned during use, including when loaded with items which may weigh hundreds of pounds. Although conventional expandable conveyors employ legs with casters or rollers for easy repositioning on, for instance, a warehouse floor, workers on occasion experience overexertion, strain and sometimes injury as a result of improper efforts to move a conveyor loaded with product. Accordingly, efficiency suffers as the conveyor remains in one place during the process of loading a truck, rather than continually being repositioned to empty portions of the truck. Alternatively, workers experience overexertion, strain or injury in attempting to do the repositioning.